The present invention pertains generally to magnetic water conditioning devices and more particularly to magnetic water conditioning devices disposed within a water heater.
Over the last several years the efficiency of commercial and residential water heaters has been improved in response to the increasing cost of fuel. One such improved efficiency design is described in U.S. Pat. No. 4,397,296. The water heater described in that patent, like most water heaters, comprises a water containing vessel, a water inlet pipe, a water outlet pipe, a combustion chamber and associated equipment.
A problem common to all water heaters, but of particular concern in high efficiency water heaters, is the formation of scale on the interior surfaces of the water containing vessel. This scale is formed from impurities in the water such as calcium salts and magnesium salts and adheres to the surfaces of the vessel including the surfaces of the combustion chamber through which heat is transferred to the water within the vessel. Scale build up on vessel surfaces, particularly combustion chamber surfaces, significantly impedes the efficient operation of the water heater by interfering with heat transfer to the water. In extreme cases, scale accumulation can cause operating temperatures of combustion chamber surfaces to rise and shorten the useful life of a water heater.
Magnetic devices have been used in the past to combat scale formation. In general, these devices operate by passing the water to be treated through magnetic fields. The scale forming salts are caused to nucleate in the water by the magnetic fields. The nucleated salts do not adhere to water heater surfaces to form harmful scale.
One of the most successful of these magnetic devices is described by Shalhoob et al in U.S. Pat. No. 4,216,092. Shalhoob describes a device to be inserted into a water heater cold water inlet pipe comprised of a non-magnetic cylindrical outer housing and a cylindrical insert contained within the housing. The housing contains the flow of water through the device and has a series of turbulence inducing circumferential ridges spaced along its length. The insert consists of a series of cylindrical magnets having their magnetic poles on their axial ends separated from one another by cylindrical spacers. Adjacent magnets have similar poles facing one another across the intervening spacers. This arrangement provides strong radial magnetic fields concentrated at the ends of the magnets. Water passing through the device flows through the magnetic fields in a direction perpendicular to the strong radial magnetic fields. Magnetic effects on ions and salts contained in the water are most pronounced when the direction of water flow is perpendicular to the magnetic fields. Salts are caused to nucleate in the flowing water rather than on the interior surfaces of the water heater vessel. The magnetically nucleated salts are then flushed from the system.
The device described by Shalhoob is a complex device. The large cylindrical insert requires that the housing have a much larger diameter than the pipe feeding water to the device in order to maintain adequate flow. Therefore, the device must be added on the water heater by cutting out a segment of the cold water inlet pipe and replacing the removed segment with the device. Moreover, the housing itself must be processed into a complex form to provide flow restriction ridges. This adds to the cost of the device. The magnetic fields of the Shalhoob device have large components perpendicular to the direction of water flow only near the magnetic poles. Over most of the length of the device, the principal direction of water flow and the magnetic fields are substantially parallel.